GB2173551A

GB2173551A - Universal bearing

Info

Publication number: GB2173551A
Application number: GB08606159A
Authority: GB
Inventors: George Nichollson Cowan
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-03-13
Filing date: 1986-03-12
Publication date: 1986-10-15
Also published as: AU5581486A; GB8506425D0; WO1986005562A1; GB8606159D0; GB2173551B

Abstract

A universal bearing for providing rotational drive between a drive member (20) and a driven member (1), allowing tilting movement of the driven member (1) relative to the driving member (20), comprises a ball bearing (7) pinned to the driven member (1), and a part-spherical seating (7A) disposed in the driving member (20). The seating (7A) is urged resiliently towards the ball bearing (7), preferably by means of a compression spring (13). Rotary drive is transmitted by a plurality of elongate bearings (11) mounted peripherally of the ball bearing (7) for reciprocating axial sliding movement in corresponding sockets in the driving member (20). The bearing may constitute a slip clutch, whose torque setting depends on the resilient bias of the elongate bearings (11) towards the driven member (1).

Description

SPECIFICATION Universal bearing The invention relates to a universal bearing supporting rotational movement of one member relative to anotherwhile allowing off-axis movement of one rotary member relative to the other.

Rotationally-driven hand tool attachments, for example sanders and nut- orscrew-drivers, are conventionally coupled rigidly to rotational driving means,for example through the chuck of an electrical hand drill. The joint between the attachment and the driving means,forexamplethe electric drill chuck, does not accommodate off axis movement of the attachment as it rotates; this places limitations on the angle atwhich the handtool is operated, rendering it unsuitable for use in particularly inaccessible corners and, in the case of rotary sanders, requiring precise control ofthe position ofthe hand tool in orderto avoid uneven surfacetreatment.Further, with such conventional rigid coupling means, varying axial th rust forces are transmitted directly to the prime mover, leading to excess wear and difficulties in control of the tool .

Accordingly, there is a demand for a more flexible coupling between the driving and driven rotary members.

The invention provides a universal bearing comprising a seating member which supports a rotary memberfor relative rotation, the rotary member comprising a first member having a cavity which receives a ball bearing such that a substantial portion of the surface ofthe ball bearing projects from the first member, the ball bearing being releasablyand rigidly connected to the first member by interlocking means, and the seating member having a part-spherical bearing cavity receiving the said projecting portion ofthe ball bearing.

In orderthatthe invention may be better understood, a preferred embodiment ofthe invention will now be described, byway of illustration only, with reference to the accompanying diagrammatic drawings in which: Figure lisa side view, partially in section, of a slip clutch incorporating a universal bearing embodying the invention; Figures 2a to 2e are side views corresponding to Figure 1 illustrating different combinations ofthe components of the slip clutch in which:: Figure 2a is a section through a first rotary member of the clutch; Figure 2b is a side view of a pin for locking a ball bearing to the first rotary member; Figure 2c is a side view ofthe ball bearing; Figure 2d is a side view, partially in section, ofthe slip clutch of Figure 1 butomittingthefirstrotary member and the pin forthe sake of clarity; and Figure 2e is a side view ofthe slip clutch of Figure 1, under a greater compressive axial load then is shown in Figure 1; Figure3a is a sectional viewofthefirst rotary memberpinnedtothe ball bearing; Figure3b is a diagram illustrating a multiple ball bearing arrangement between the main ball bearing and its seating;; Figure3c is a furtherdiagram illustrating partofthe second rotary member ofthe slip clutch of Figure 1; Figure 3d is a transverse section taken on the line A-AofFigure3c; and Figure 4 is a top plan view ofthe slip clutch of Figure 1.

The slip clutch incorporating a universal bearing comprises a first rotary member 1 cupled to a second rotary member 20 by way of a spherical ball bearing 7. The first rotary member 1, shown most clearly in Figure 2a, consists of a diskwith a flat upper surface and a lower surface having a part-spherical recess 6 which seats the ball bearing 7 and is complementary in shape thereto. Two colinear radial bores 2through the disk 1 communicate with the recess 6 and receive a connection pin 3which is also threaded through a bore 72 through one side, the upper side, of the ball bearing 7.The connection pin 3 thus rigidly secures the ball bearing 7 to the first rotary member 1.

The surface of the ball bearing 7 remote from the pin 3 is seated in a cup-shaped, part-spherical seating 7A byway of a ball bearing arrangement consisting of a plurality of balls 9 whose diameter is substantially smallerthanthatofthe ball bearing 7.

The smaller balls 9 are free to roll between the spherical outersurface ofthe ball bearing 7 and the spherical inner surface ofthe seating 7A.

The second rotary member 20 comprises two telescopically-connected cylindrical members 12,17, of which the overlapping ends are provided with respective stops, or piston type rings 14, 141 which actas stops. The outercylindrical member 17 has thin walls and a closed base. The inner cylindrical member 12 hasthickerwallsthantheoutercylinder and has eight cylindrical sockets bored parallel to its axis and disposed at equi-angular positions in the cylinderwall, as shown in Figures 3d and 4,fora purpose to be described below.

A coil compression spring 13 is accommodated axially ofthe inner and outer cylinders 17,the lower end of which spring abuts the inner surface of the base ofthe outer cylinder 17, and the upper end of which is secured to the outer surface ofthe seating 6 forthe ball bearing 7. The compression spring 13 thus resiliently urges the seating 7A axially away from the second rotary member 20.

As shown most clearly in Figure 2d and in Figure 3b, the ball bearing 7 is retained in its seating 7A against axial displacement away from the seating 7A by means of a centrally-apertOureddisk p plate 21 secured over the seaming 7A and constituting an end closureforthe otherwise open innercylinder12.The diameter ofthscentral aperture in the disk plate 21 is slightly smallerthan the diameter of the ball bearing 7, and the larger part ofthe ball bearing 7, and the larger part ofthe ball bearing 7 is disposed between the seating 7A and the disk plate 21, so that the ball bearing 7 is retained by the circularedge of the disk plate 21 bearing againstthe surface ofthe ball bearing 7. The disk plate 21 also serves to retain the smaller ball bearings 9 in the gap between the seating 7A and the ball bearing 7.

Rotational drive is transmitted between thefirst and second rotary members 1,20, by means of eight elongate bearings 11 which are received in the respective eight elongate sockets in the wall of the inner cylinder 12. As shown in Figure 1 and Figure 2d, each elongate bearing 11 is constrained to slide axially in its corresponding socket, and is urged resiliently towards the first rotary member 1 by means of a respective coiled compression spring 18 mounted in the socket between the base of the socket and an end surface of the elongate bearing 11. The other end 10 of each elongate bearing 11 has a part-spherical bearing surface which bears against a corresponding concave part-spherical bearing surface 5 formed as a recess in a peripheral portion of the underside of the first rotary member 1, as shown in Figure 2a.The part-spherical recesses 5 are equi-angularly disposed around the periphery of the first rotary member 1, at positions corresponding to the sockets in the wall of the inner cylindrical member 12. The elongate bearings 11 are free to pivot relative to the axis of the first rotary member 1, so as to accommodate off-axis movement of the first rotary member 1 relative to the second rotary member 20. The elongate members 11 transmit rotational drive through their bearing surfaces 10 tangentially to the corresponding side walls of the-recesses 5 in the first rotary member 1, thus transmitting rotational drive between the first and second rotary members 1,20.

It will be appreciated that the elongate bearings not only provide the rotational drive but also function as stabilizing bearings, resiliently resisting off-axis tilting movement of one rotary member relative to the other.

The first rotary member 1 is removable or replaceable, by removing the connecting pin 3 and lifting the first rotary member 1 away from the remainder of the universal bearing joint. The elongate bearings 11 remain in their sockets in the second rotary member 20, and are preferably retained therein by suitable stops (not shown). It is thus possible to use the same rotational drive means, for example an electric power drill, coupled rigidly to the second rotary member 20, to drive several different rotary attachments, for example sanders or nuts- or screwdrivers, each attachment being coupled rigidly to a different first rotary member 1.

The universal bearing is lubricated as follows. As shown in Figure 2c, the ball bearing 7 has a further lubrication channel 8 bored axially through part of the sphere and linking the centre ofthe main bore 72 for the connecting pin 3 with the outer surface of the sphere adjacent the centre of the seating 7A. The ball bearing 7 is thus provided with a lubrication network having a "T" shape. The connecting pin 3, as shown in Figure 2b, is provided with an internal lubrication channel 4 communicating one open end of the pin 3 with three or more lubrication ports 41 disposed along the length of the connecting pin 3.

As shown in Figure 2a, still further lubrication channels 51 are provided in the first rotary member 1 linking the main bore 2 forthe connecting pin 3 with each ofthe part-spherical recesses 5 for the elongate bearings 11.

Thus lubrication of all the moving parts is provided from a single point, namely the open end of the connecting pin 3, from which lubricating fluid passes through the ports 41 and along the main bore 2, firstly through the further bore 8 to the seating 7A, and secondly through the lubrication channels 51 to the part-spherical recesses 5.

As an alternative to the coiled compression spring 13, the second rotary member 20 may be sealed against the flow of fluid from its exterior, and the resultant fluid compression spring constituted by the fluid within the second rotary member 20 performs the same function of resiliently urging the seating 7A away from the base of the outer cylindrical member 17. The fluid may be air or a suitable compressible liquid such as freon.

Preferably, with such a fluid spring, the seating 7A rigidly secured to the disk plate 21 or to some other portion of the inner cylindrical member 12.

The slip clutch functions as follows. Rotational drive applied to one of the rotary members, preferably to the second rotary member 20, is transmitted to the other rotary memberthrough the elongate bearings 11, while compressive thrust forces on the first and second rotary members 1, 20 are supported by the ball bearing 7 and the compression spring 13. Off-axis movement of the two rotary members 1,20 is accommodated, at least up to an angle of 30 or 40 , by the sliding movement ofthe ball bearing 7 in its seating 7A and by the axial sliding movement of the elongate bearings 11 in their sockets.When one rotary member rotates off the axis ofthe other rotary member, it will be appreciated that the elongate bearings 11 reciprocate in their sockets with a frequency equal to the frequency of rotation, and with an amplititude corresponding in size to the extent to which one rotary member lies off the axis of the other.

The clutch action is as follows. Below a predetermined level of to rque applied between the first and second rotary members 1,20, the elongate bearings 11 lodge in the corresponding recesses 5 in the first rotary member 1, and the bearing is locked to transmit drive. Above that torque level, the elongate bearings 11 slide out of their recesses 5, against the resilient bias of the springs 18 in the sockets, allowing relative rotation of the rotary members 1,20 and thus slipping ofthe clutch. The said predetermined torque level depends on the spring constant of the springs 18.

In an alternative form of slip clutch,the eight recesses 5 are replaced by a single annular recess 5 ofthe same sectional shape as shown in Figure 2A.

The clutch then slips unless the force on the elongate bearings 10 is sufficient to provide a sufficient dynamic frictional force tangentially between the surfaces 11 of those bearing 10 and the recess 5. Thus the torque setting again depends on the strength of the springs 18.

Whilst the invention has been described with reference to particular characteristics of the described embodiment, many modifications and variations thereof are possible within the scope of the invention.

in one such variation, the second rotary member 20 functions instead as a stationary platform, while the first rotary member 1 is free to tilt off axis and/or rotate about its axis. One application of such a universal bearing is in a rotatable display stand for postcards, for example, in which the first rotary member is connected to a vertical spindle on which display racks are mounted, and the second rotary member 20 rests on the ground.

In another variation, the second rotary member 20 is again mounted stationarily, while rotational drive is imparted to the first rotary member by external drive means.

In both these variations, the elongate bearings 11 have an important stabilizing function, limiting and resiliently resisting the off-axis tilting movement of the first rotary member, whether or not it is rotating.

Claims

1. A universal bearing comprising a seating member which supports a rotary member for relative rotation, the rotary member comprising a first member having a cavity which receives a ball bearing such that a substantial portion of the surface of the ball bearing projects from the first member, the ball bearing being releasably and rigidly connected to the first member by interlocking means, and the seating member having a partspherical bearing cavity receiving the said projecting portion of the ball bearing.

2. A universal bearing according to Claim 1, further comprising a stabilizer bearing peripheral to the ball bearing between facing surface of the said first member and of the seating member to allow relative rotation thereof but to limit relative tilting movement thereof to a predetermined extent.

3. A universal bearing according to Claim 1, comprising drive means removably coupling the seating and rotary members to provide rotational drive therebetween.

4. A universal bearing according to Claim 2, wherein the stabilizer bearing constitutes drive means removably coupling the seating and rotary members to provide rotational drive therebetween.

5. A universal bearing according to any preceding claim, wherein the seating member comprisesa housing to which is coupled a seating member comprises a housing to which is coupled a seating which has the said part-spherical bearing cavity.

6. A universal bearing according to Claim 5 wherein the seating member housing comprises means resiliently urging the seating against the said ball bearing to provide a reaction to compressive thrust loads between the seating and rotary members.

7. A universal bearing according to Claim 6, wherein the said housing is sealed, and the resilient urging means comprises a fuid compression spring.

8. A universal bearing according to Claim 6, wherein the resilient urging means comprises a mechanical compression spring retained in the housing and engaging, at one end, the seating and, at the other end, a base of the housing.

9. A universal bearing in accordance with any preceding claim, wherein the interlocking means is a connecting pin through at least part of the ball bearing and part ofthe first member.

10. A universal bearing according to Claim 9 wherein the ball bearing is provided with a bore through which the connecting pin connects the bore to the first rotary member.

11. A universal bearing according to any preceding claim, wherein the said cavity in the first member is a part-spherical recess complementary to the ball bearing surface.

12. A universal bearing according to Claim 5, or to any preceding claim appendant to Claim 5, wherein one end ofthe housing has an opening of circular internal cross section which receives the seating for the ball bearing.

13. A universal bearing according to Claim 12, wherein the housing is in two, telescopically interconnected parts, of which the part closer to the said ball bearing at the said end ofthe housing defines the said opening for the seating.

14. A universal bearing according to Claim 12 or 13, wherein the ball bearing is retained in the seating by means of an apertured retaining plate attached to the said end of the housing, the said bearing extending through the said aperture in the plate.

15. A universal bearing according to Claim 14, wherein the said aperture is circular and of a diameter smaller than that of the ball bearing, the edge of which aperture bears against the spherical surface of the ball bearing on its side remote from the seating to retairi it therein.

16. A universal bearing according to Claim 13, 14 or 15 wherein each said part is generally cylindrical.

17. A universal bearing according to Claim 16, wherein the said part receiving the seating has the lesser diameter of the two parts.

18. A universal bearing according to Claim 16 or 17, as appendant to Claim 14, wherein the said apertured retaining plate is a centrally-apertured disc plate.

19. A universal bearing according to any of Claims 12 to 18 as appendantto Claim 3, wherein the drive means comprises a plurality of elongate bearings disposed parallel to the axis of the said end of the housing and peripherally surrounding the said ball bearing, each elongate bearing being constrained to axial sliding movement in the seating member a j coupled, at its end remote therefrom, to the rotary member to provide tangential rotary drive therebetween but to allow pivotal movement of the elongate bearing relative to the axis ofthe rotary member.

20. A universal bearing according to Claim 19, wherein each elongate bearing is received in a corresponding one of a plurality of sockets arranged in the seating member peripherally of the said ball bearing, which sockets have means resiliently urging the elongate bearing axially towards the rotary member.

21. A universal bearing according to any preceding claim, wherein the said bearing cavity is defined by a part-spherical shell.

22. A universal bearing according to any preceding claim, wherein the bearing cavity includes a multiple ball bearing arrangement comprising balls of a diameter substantially smaller than that of the said ball bearing, disposed for rolling motion in the said cavity and against the outer surface of the said bearing.

23. A universal bearing according to Claim 10 or to any preceding claim appendant to Claim 10, wherein the said first member has at least one bore aligned with the said bore in the ball bearing, to receive the connecting pin.

24. A universal bearing according to Claim 10, or to any preceding Claim appendant to Claim 10, wherein the ball bearing has a further bore linking the said bore to the surface of the ball bearing adjacent the bearing cavity to provide a lubrication channel linking the bearing cavity with the said first member.

25. A universal bearing according to Claim 10, or to any preceding Claim appendant to Claim 10, wherein the said connecting pin mounted through the said bore has an internal lubrication channel communicating at least two external ports.

25 30 35

26. A universal bearing according to Claim 19, or to any preceding Claim appendant to Claim 19, wherein the said first member comprises a plurality of recesses against respective ones of which bear the said remote ends of the elongate bearings.

27. A universal bearing according to Claim 19, or to any of claims 20 to 25 an appendant to Claim 19, wherein the first member comprises an annular recess against which bear the said remote ends of the elongate bearings.

28. A universal bearing according to Claim 25, wherein lubrication channels are provided to link the said at least one bore in the first rotary member with the said recesses, to lubricate the elongate bearings.

29. A universal bearing substantially as described herein with reference to the accompanying drawings.